Magnetic separation has been historically active in several different industries and has only recently been utilized in petroleum refining. Development of economical permanent magnets with high magnetic strength has led to a new process that separates less active (high metals) catalyst particles from equilibrium FCC catalyst, producing a higher activity/lower metals catalyst for recycle.
As the cost of operating a refinery increases due to environmental constraints, as well as increases in raw material and maintenance costs, refiners look for processes which improve refining margins with the least amount of capital investment. Fluidized catalytic cracking (FCC) in particular has a significant bottom line effect on both refining revenue generation and cost. FCC costs include virgin catalyst purchase as well as spent catalyst disposal, which can be significant at times. Both of these can be offset to a degree by utilization of a new process that removes the older, higher metals laden, less active catalyst from the circulating inventory by dry magnetic separation techniques, to produce a lower metals/higher activity and higher selectivity catalyst.
Magnetic separation techniques have been around for years in the mining, food and other industries. These techniques include the utilization of eddy currents, electromagnets and permanent magnets for separation of magnetic from non-magnetic material on a wet or dry basis. Electromagnets use electricity to induce a magnetic field in a metallic object by flowing electrons through a wire-wound core to induce a magnetic field in a metal object in the center of the core. These types of magnets are relatively expensive and operating costs are usually high due to the consumption of electricity. Permanent magnets are generally used in operations where the material being removed exhibits strong ferromagnetic and/or paramagnetic properties.
Magnetic separation of metals-contaminated equlibrium catalyst (ECat) from ECat particles having a lower metal content has recently been commercialized. Aspects of this process are disclosed in one or more of U.S. Pat. No. 4,406,773 to Hettinger, Jr. et al.; U.S. Pat. Re. 35,046 to Hettinger, Jr. et al.; U.S. Pat. No. 5,147,527 to Hettinger, Jr. et al.; U.S. Pat. No. 5,171,424 to Hettinger; U.S. Pat. No. 5,190,635 to Hettinger; U.S. Pat. No. 5,198,098 to Hettinger, Jr.; U.S. Pat. No. 5,230,869 to Hettinger et al.; U.S. Pat. No. 5,328,594 to Hettinger; U.S. Pat. No. 5,364,827 to Hettinger et al.; U.S. Pat. No. 5,393,412 to Hettinger; U.S. Pat. No. 5,538,624 to Hettinger; all of which are hereby incorporated by reference. Some other work has been done in the area of magnets separation of FCC catalyst. U.S. Pat. No. 5,250,482, to Doctor, which is hereby incorporated by reference, used a super-cooled, quadrupole open-gradient magnetic separation system to separate ECat having more than about 2000 ppm nickel equivalents from ECat having less about 2000 ppm nickel equivalents.